Cobalt (Co) is a metal that is added to steel to improve its remittance to coron

Question

Cobalt (Co) is a metal that is added to steel to improve its remittance to coronation. Calculate both the number of moles in a sample of cobalt concerning 5.00 times 10^20 atoms and the mass of the sample. Cobalt's MW = 58.93 grams/mole. A pile of marbles weighs 394.80 grams; 10 marbles weigh 37.60 grams. How many marbles are in the pile? Given Cu's (the mass of one atom of copper = 63.55 am u), what is the mass of 1 atom of copper? Given the following reaction (w/25 kg of Nitrogen (N_2(g)) and 5 kg of hydrogen (H_2(g)): N_2(g) + 3H_2(g) rightarrow 2NH_3(g) (i) Determine which reactant is the limiting reagent. (ii) How much NH_3(g) is produced from the reaction? Chapter 4 - Types of Chemical Reaction and Solution Stoichiometry what is the most comment solvent? why is water a polar molecule? Define the solubility of a substance in water? (i) How soluble is sodium chloride (NaCl) in water? (ii) How soluble is silver chloride (AgCl) in water? what is a solute and solvent? what is the difference between a nonelectrolyte, a weak electrolyte, and a strong electrolyte? (i) what is an acid?(ii) what is a base? b) Quantitative Section

Explanation / Answer

32)

the weight of pile of marbles = 394.80 grams

the weight of 10 marbles = 37.60grams

so weight of 1 marble = 37.60 / 10 = 3.76 grams

so number of marbles in pile = weight of pile of marbles / weight of each marble = 394.80 / 3.76 = 105

33) the atomic mass of copper = mass of 6.023X 10^23 atoms of copper = 63.55

so weight of one atom of copper = 63.55 / 6.023 X 10^23 grams = 10.55 X 10-23 grams

34) The reaction is N2 + 3H2 --> 2NH3

which shows that 1 mole of N2 will react with 3 moles of H2

Or 28 grams of N2 will react with 6grams of H2

so the ratio of weights of N2/H2 = 28 / 6 = 4.67

The given weight ratio = N2 / H2 = 25 / 5 = 5

which is higher than required so weight of N2 is more or it is in excess and H2 is the limiting reagent

b) 28 grams of N2 will react with 6grams of H2 to give 34 grams of NH3

or 6 grams of H2 will react with 28 grams of N2 to give 34 grams of NH3

So 5Kg of H2 will react with 28 X 5 / 6 Kilograms of N2 to give 34 X 5 / 6 Kilograms of NH3

5Kg of H2 will react with 23.33 Kg of N2 to give 28.33Kg of NH3

Chapter 4

35) the most common solvent = water

36) due to presence of highly electronegative oxygen and electropositive element hydrogen there is generation of polarity in the molecule.

Oxygen atom pull electrons twoards itself from hydrogen generating a negative charge on oxygen and a positive charge on hydrogen

37) a substance is soluble in water if it is polar. Like dissolves like

38) NaCl is highly solulbe in water while AgCl is not soluble in water and will ppt out

39) the substance which taken in smaller amount is solute and dissolved in other substance which is in larger amount is solvent

40) a non electrolyte : it will not dissociate into ions when dissolved in water

Example : glucose

Weak electrolyte: it will be soluble in water and will incompletely dissociated in water

eXample: NH4OH

Strong electrolyte: it will be soluble in water and will be completely dissociated in water

Example: NaCl

41) an acid a substance which will give H+ and base is a substane whcih will accept H+

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